2006-12-30 02:44:26 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
OK
99% of Gas(petrol) cars are 4 stroke engines. The air is drawn into the engine by a vacuum created during the intake stroke.
(The 4 stroke cycle Power, Exhaust,Intake,Compression and takes two crankshaft revolutions to complete)
Diesels engines are also 4 stroke AND 2 stroke.
4 stroke engines operate in a similar fashon to gas(petrol) cars except in the means of ignition...
2 stroke cycle uses a Blower to force fresh air into the cylinder and scavenge the exhaust air. Scavenging is blowing the exhaust out of the cylinder
(2 stroke cycle Power, Scavange at BDC, Compression) Notice a 2 stroke has 1 power stroke for every revolution of the crankshaft...
Vacuum pump:
The 4 stroke engine may use some of its vacuum generated for accessories attached to the engine like vacuum advance and brake boost.) Excessive use of vacuum and vacuum leaks negatively impacts the efficiency of the engine...
If this is a large truck a suspect a vacuum pump is used with an electric clutch as a means of increasing efficiency and to supply a large vacuum demand.
There are air blowers attached to the 2cycle diesels to provide scavenge air under pressure to the cylinders.
2006-12-30 08:07:40 · answer #1 · answered by MarkG 7 · 0⤊ 0⤋
There is no need for a vacuum pump on a diesel engine.
It operates on a Carnot Cycle with a higher compression ratio.
Its fuel is injected at 14.7 Atmospheres.
It has a higher Thermal Efficiency than petrol.
2006-12-30 19:17:17 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Turbo diesel has a vacuum pump. Simple diesel engines do not need vauum pumps!
2007-01-01 00:53:21 · answer #3 · answered by Mesab123 6 · 0⤊ 0⤋
It is used to evacuate the combustion products from the combustion chamber. This is necessary so there will only be pure, compressed air when the fuel is injected. This is not mandatory, but greatly increases the possible power generated on each stroke.
Two stroke engines (gasoline) accomplish much of this with a mechanism called a scavenger, which works on inertia if incoming air.
2006-12-30 03:43:50 · answer #4 · answered by Anonymous · 0⤊ 2⤋
The fuel feed system on a diesel engine can only function in a vacuum. That's why; if you run out of fuel in a diesel you have to get the fuel system bled.
2006-12-30 02:56:27 · answer #5 · answered by Anonymous · 0⤊ 2⤋
petrol engines produce a vacumn on the induction stroke which is utilised by the braking system
2006-12-30 02:46:14 · answer #6 · answered by cereal killer 5 · 2⤊ 0⤋
Diesel is stronger.
2006-12-30 02:48:28 · answer #7 · answered by spir_i_tual 6 · 0⤊ 3⤋